The PowerShot A400 is equipped with a 2.2x 5.9 - 13.2mm (45 - 100mm in 35mm format) optical zoom lens with a maximum aperture of f3.8. The all-glass lens is designed with 9 elements in 7 groups. The lens is not threaded for any accessories to screw into. When powered down, the lens retracts inside the body and is protected by a sliding lens barrier.

The 9-point AiAF focusing system (or user-selectable Center AF point) works from 1.5 ft. (47cm) to infinity in normal mode and in Macro its focus range is 2.0 in. (5cm) to 1.5 ft. (47cm.) It also features a built-in focus assist illuminator.

The built in flash has modes for Auto, Forced On, and Forced Off. Red-eye reduction can be enabled or disabled via the Rec. mode menu. The working range is Normal: 47 cm - 2.0 m (1.5 - 6.6 ft.) and Macro: 30 cm - 47 cm (1.0 - 1.5 ft.) when the ISO sensitivity is set to Auto.

The real-image zoom optical viewfinder shows approximately 80% - 85% of the captured image. There is no diopter adjustment. The two LEDs on the right indicate focus, flash, and image processing status.

Controls on the back: DISPlay button toggles the color LCD OFF/ON and also controls the amount of data overlayed on the screen. The FUNCtion button gives you access to options for selecting the exposure compensation, white balance, image size, quality, ISO speed and color effects. In playback mode it is the image delete button. The rocker switch controls the zoom, and in playback mode it magnifies the image up to 10x or calls up the index screen. The Mode switch changes the camera from PlayBack, Record, SCN, and movie modes. The MENU button calls up or dismisses the onscreen menu system in both record and playback modes. The 4-way selector allows you to navigate the menu options, pressing "Up" changes the metering mode, "Right" toggles the flash, "Down" controls the drive mode, and "Left" changes the focus mode. The Set button accepts selections. The Print/Share button allows you to quickly and easily print and transfer images.

On top is the shutter release and power button. You can also see the camera's built-in speaker for playing back audio in-camera.

The PowerShot A400 is equipped with a SD card slot and is compatible with any size Secure Digital. The camera ships with a 16MB SD card. Simply press the card "in" to eject the it. Shown here with a spacious and speedy SanDisk Ultra II 512MB SD card.

The I/O ports include the DIGITAL (USB 1.1 compatible) port for connection to the host computer's USB port or to a PictBridge compatible printer. An optional AC adapter, Canon CA-PS800, can be connected to the DC IN port. And a Audio/Video out port for connecting to a TV set (NTSC or PAL selectable.)

Power is supplied by two AA-type batteries. The batteries are housed under the same door as the SD card. Canon supplies a set of alkaline batteries, but I highly recommend the use of high-capacity NiMH rechargeables which are more environmentally friendly, last longer, and save you money.